1. Field of the Invention
The invention relates generally to microprocessor based systems and more particularly to the detection of abnormal operating conditions and reinitiation of normal operation.
2. Description of the Prior Art
During the operation of a microprocessor an interrupt in power or system malfunction requires the restart of the system. A reset terminal on the microprocessor provides the necessary toggle to restart the system, and numerous prior art techniques have been presented to sense system malfunction and reset the microprocessor.
One of such prior art techniques is presented in U.S. Pat. No. 4,586,179 which monitors a microprocessor output terminal for a status signal and activates a reset trigger on failure of the status signal. Additionally, the reset trigger is initiated on sensing of a supply voltage drop. To accomplish these objectives, the microprocessor status signal is processed through a complicated circuit including a timing circuit and a triggering transistor to pulse the microprocessor reset pin. A voltage separate sensitive circuit is also used to reset the timing counters and in that fashion, to activate the triggering transistor and reset the microprocessor following detection of low voltage.